Table 2.
Summary estimates of sensitivity, specificity, diagnostic odds ratio, and their 95% confidence intervals of US, MRI, and FDG PET.
| Imaging Technique | N Studies | Sensitivity | I2 | Specificity | I2 | DOR |
|---|---|---|---|---|---|---|
| US | 30 | 0.55 (0.49, 0.62) | 90.01 | 0.99 (0.97, 1.00) | 95.06 | 112 (39, 320) |
| US grayscale | 24 | 0.63 (0.56, 0.69) | 88.86 | 0.88 (0.82, 0.92) | 93.91 | 12 (8, 18) |
| US + FNA|CNB | 20 | 0.51 (0.43, 0.59) | 88.44 | 1.00 (0.99, 1.00) | 94.19 | 752 (98, 5765) |
| FNA | 14 | 0.78 (0.73, 0.83) | 55.40 | 0.99 (0.96, 1.00) | 48.73 | 560 (91, 3451) |
| MRI | 10 | 0.83 (0.72, 0.91) | 75.81 | 0.85 (0.72, 0.92) | 93.00 | 28 (16, 51) |
| MRI without DWI | 7 | 0.81 (0.49, 0.95) | 89.17 | 0.84 (0.74, 0.91) | 89.04 | 22 (7, 72) |
| MRI with DWI | 4 | 0.78 (0.60, 0.89) | 79.35 | 0.90 (0.82, 0.95) | 67.07 | 33 (17, 65) |
| DWI alone | 5 | 0.74 (0.50, 0.89) | 83.54 | 0.78 (0.51, 0.92) | 93.63 | 10 (5, 19) |
| PET FDG | 24 | 0.49 (0.39, 0.59) | 87.03 | 0.94 (0.91, 0.96) | 73.98 | 15 (8, 26) |
| PET FDG without CT | 9 | 0.44 (0.28, 0.62) | 90.90 | 0.95 (0.91, 0.97) | 0 | 14 (5, 44) |
| PET FDG with CT | 15 | 0.51 (0.40, 0.63) | 86.04 | 0.93 (0.89, 0.96) | 79.51 | 14 (8, 27) |
CNB: Core Needle Biopsy; CT: Computed Tomography; DOR: Diagnostic Odds Ratio; DWI: Diffusion Weighed Imaging; FDG: Fluorodeoxyglucose; FNA: Fine Needle Aspiration; MRI: Magnetic Resonance Imaging; PET: Positron Emission Tomography; US: Ultrasonography. The diagnostic odd ratio (DOR) values obtained with different combinations of sensitivity and specificity could be used as a single summary measure. It was defined as the ratio of odds of positivity in disease relative to non-diseased. The DOR value ranges from 0 to infinity, and a higher value signifies better diagnostic performance. A value of 1 indicates that a test cannot distinguish between patients with or without the disease and values of <1 introduce more FN results among the diseased [22]. Confidence intervals consider the heterogeneity beyond chance between studies (random effects models). The impact of unobserved heterogeneity is traditionally assessed statistically using the quantity I2. It describes the percentage of total variation across studies that is attributable to the heterogeneity rather than chance [22]. Magnetic resonance imaging (MRI) had a significantly higher sensitivity than other imaging modalities, whereas Ultrasonography (US) had a significantly higher specificity than MRI and to a lesser extent than fluorodeoxyglucose positron emission tomography (PET). DOR estimated for US was significantly greater than those of MRI, which in turn was significantly greater than those of FDG PET. Further analysis revealed that for all imaging modality, US + fine needle aspiration (FNA) or core needle biopsy (CNB) had the highest DOR value. For MRI studies, MRI with diffusion weighted imaging (DWI) had the highest DOR value and for PET studies. PET with or without computed tomography (CT) had the same DOR value.